1. Field of the Invention
The present invention relates to a foamed product integral with trim cover assembly for use in automotive seat, such as a headrest or an armrest, which is formed by subjecting a three-dimensional trim cover assembly to foaming process entailing the steps of injecting a liquid foaming agent into an inside of the trim cover assembly and curing the liquid foaming agent into a foam padding filled in the trim cover assembly in an integral manner. In particular, the invention is directed to a foamed product of this kind which has, provided therein, a frame element including a portion projecting outwardly from the foamed product. A typical example thereof is a headrest of the type having: a frame element provided therein; and a part of the frame element projecting, as a headrest stay (s), outwardly therefrom.
2. Description of Prior Art
As stated above, it should be noted that the term “foamed product integral with trim cover assembly” is a generic term which generically refers to a foam product formed integrally together with a three-dimensional trim cover assembly, which is typically formed through the following known steps of: injecting a liquid foaming agent into the inside of the trim cover assembly preformed in a predetermined shape and placed in a given die means; and then curing the liquid foaming agent into an increased mass of foam material (e.g. foam padding) filled in the trim cover assembly.
Various sorts of the foregoing foamed product integral with trim cover assembly for use in automotive seat have been made available on the market. Among them, known is a foamed product of this kind which is of the structure having a frame element provided therein, with a part of the frame element projecting outwardly from the foamed product.
For example, in the case where a typical headrest having a pair of stays projected therefrom is formed by foaming process, first of all, a substantially inverted-U-shaped frame is preformed, which has a pair of stay portions defined integrally in the respective two rectilinear free end portions thereof, and also, a three-dimensional trim cover assembly is preformed in a predetermined shape of headrest, which has, formed in the bottom wall thereof, a transversely extending elongated opening for allowing ingress of the foregoing frame therethrough into the inside of the trim cover assembly, and a pair of holes for allowing the foregoing pair of stay portions of the frame to pass therethrough, respectively. In that trim cover assembly, such transversely extending elongated opening is defined between two extensions respectively of two cover materials forming the bottom wall of trim cover assembly. More specifically, those two extensions are both of a length substantially equal to an entire width of the bottom wall of trim cover assembly and bent at substantially a right angle in a direction inwardly of the trim cover assembly, thus defining therebetween the foregoing elongated opening which extends transversely of the bottom wall of trim cover assembly.
Then, the frame is inserted and placed via such elongated opening in the inside of the trim cover assembly, while projecting the pair of stay portions of the frame through the respective afore-said pair of holes to the outside of the trim cover assembly, thereby providing a basic headrest unit. This basic headrest unit is placed in a foaming die, and a liquid foaming agent is injected in the inside of trim cover assembly and cured into a mass of foam padding filled in the trim cover assembly in an integral manner, so that a resultant headrest with two stays is produced.
In this sort of foamed product integral with trim cover assembly, it has been a technical concern that, during the foaming process, the liquid foaming agent will be leaked through the elongated holes as well as through the two holes through which the respective two stay portions pass. To prevent such leakage of liquid foaming agent, the Japanese Laid-Open Patent Publication No. 5-35052 teaches the following points: (i) a horizontal covering portion and a folded horizontal covering portion are provided in an opening region corresponding to the afore-said elongated opening in the bottom wall of trim cover assembly, and the folded horizontal covering portion is juxtaposed on and sewn with the horizontal covering portion to prevent leakage of liquid foaming agent through the opening region, and (ii) a tubular sealing material is provided to each of the two stay portions at a point adjoining the afore-said hole through which each stay portion passes, to thereby prevent leakage of liquid foaming agent through that particular hole.
However, even in the foregoing prior art, the trim cover assembly used per se is of an elastically deformable property and formed in a three-dimensionally closed configuration, and the foregoing two covering portions are both formed from the same materials as those of that trim cover assembly. Consequently, when a liquid foaming agent is injected in such trim cover assembly and cured into an increased mass of foam padding filled therein, a whole of the trim cover assembly is swollen outwardly, so that the foregoing two sewn horizontal covering portions are subjected to slight relative movement in a direction opposite to each other as well as to deformation in any angle, thus creating small interstices between the two sewn horizontal covering portions. As a result thereof, the liquid foaming agent is leaked through such small interstices to the outside of the trim cover assembly during foaming process. Further, the formation of the two sewn covering portions and the provision of the tubular sealing material to the stay portions not only require much labors and skill on the worker's side, but also increase costs for assembly of the headrest.